CVE-2026-6733

What it is

Impact: Undici's HTTP/1.1 client is vulnerable to response queue poisoning on reused keep-alive sockets. An attacker-controlled upstream server can inject an unsolicited HTTP/1.1 response onto an idle socket after a request completes. When the client dispatches the next request on that socket, it associates the injected response with the new request, causing responses to be delivered to the wrong requests. This requires an attacker-controlled or compromised upstream HTTP/1.1 server and keep-alive connection reuse. Patches: Upgrade to undici v6.26.0, v7.28.0 or v8.5.0. Workarounds: Disable keep-alive connection reuse by setting keepAliveTimeout: 0 on the Client or Pool.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-06-17 18:18 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-27 23:46 UTC Last updatedMost recent change to the record

Details

Published

2026-06-17 18:18 UTC

Last modified

2026-06-27 23:46 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-367

Record status

Analyzed

Affected

• Nodejs Undici < 6.27.0
• Nodejs Undici < 7.28.0
• Nodejs Undici < 8.5.0

Attack profile CVSS 3.1 · 3.7

Attack vector

Network

Complexity

High

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

None